Technical Field
This application relates generally to systems and methods for treating waste water, and more particularly to systems and methods for removing iron from waste water, including produced water and flowback fracturing water.
Background
Oil and gas exploration and recovery typically generate large amounts of contaminated water, such as flowback fracturing water and produced water. Flowback fracturing water, or flowback water, is water that is returned to the surface of a hydraulic fracturing site after it has been injected into shale beds to fracture the shale. Produced water is water that occurs naturally and may flow to the surface of a well throughout the lifespan of the well. Flowback water is unique to hydraulic fracturing and may comprise clays, chemical additives, hydrocarbons, dissolved metal ions (e.g. Fe2+ and Fe3+), naturally occurring radioactive materials (e.g. radium) and total dissolved solids (TDS). Produced water typically comprises high levels of dissolved metal ions (e.g. Fe2+ and Fe3+) and TDS such as barium, calcium, iron and magnesium. Produced water may also contain hydrocarbons and naturally occurring radioactive materials.
Many of the chemicals in flowback water and produced water may interfere with any subsequent reuse of the water and should be filtered prior to reuse. For example, iron may lead to corrosion and clogging of equipment, clogging of downhole formations, an increased need for additive chemicals, and membrane fouling (e.g. filters). Iron levels in flowback water and produced water may also be subject to regulation by government authorities.